1. Technical Field
This disclosure relates to techniques for video rendering. This disclosure was developed with attention paid to its possible use, e.g., in video reproducing systems arranged upstream of a display device capable of receiving as an input a video data stream.
2. Description of the Related Art
Free Viewpoint Video (FVV) is a designation for the capability of a rendering engine to interactively control the viewpoint while rendering/displaying a video signal.
Three-Dimensional Video (3DV) is a designation for the capability of a display system/device to provide the viewer with a 3D impression while watching a video.
FVV represents one of the most exciting applications of next-generation television, adding a further degree of freedom to the usual way of watching TV.
For instance, the paper by C. L. Zitnick, S. B. Kang, M. Uyttendaele, S. Winder, and R. Szeliski, “High-Quality Video View Interpolation Using a Layered Representation”, ACM SIGGRAPH and ACM Trans. on Graphics, Los Angeles, Calif., USA, August 2004 describes a multi-camera system to simultaneously capture a dynamic scene and rendering algorithms which allow synthetic viewpoints to be generated on-the-fly during a real-time user interaction session.
The techniques available to obtain such an effect can be classified in two basic families, namely:                Model-based Rendering, which operates on a geometrical model of the scene and transforms it by means of Computer Graphics (CG);        Image-based Rendering, which operates at the pixel-level and warps the image by using some kind of information related to the distance of the scene from the camera.        
The former approach is usually more expensive from a computational point of view, as it may use a graphic card to perform the great amount of computation, and is obviously more suitable for managing synthetic data than real-world scenes.
The latter approach treats each pixel separately, and operates within a framework where no mathematical models are used to describe entities. Hence it is more suitable for real-word scenes.
The 3DV functionality can be achieved in the same way of the FVV by taking into consideration the principle of stereoscopy: a three-dimensional impression may be obtained by conveying to the viewer's eyes two adjacent views of the same scene related to two different positions located approximately 6.5 centimeters from each other, which corresponds to the average distance between a human's eyes.